--- ray/src/rt/pmapsrc.c	2015/05/28 12:27:22	2.6
+++ ray/src/rt/pmapsrc.c	2016/05/17 17:39:47	2.13
@@ -1,3 +1,6 @@
+#ifndef lint
+static const char RCSid[] = "$Id: pmapsrc.c,v 2.13 2016/05/17 17:39:47 rschregle Exp $";
+#endif
 /* 
    ==================================================================
    Photon map support routines for emission from light sources
@@ -7,8 +10,7 @@
    (c) Lucerne University of Applied Sciences and Arts,
    supported by the Swiss National Science Foundation (SNSF, #147053)
    ==================================================================
-   
-   $Id: pmapsrc.c,v 2.6 2015/05/28 12:27:22 greg Exp $
+ 
 */
 
 
@@ -523,16 +525,21 @@ void getPhotonPorts ()
 /* Find geometry declared as photon ports */
 {
    OBJECT i;
-   OBJREC* obj;
+   OBJREC *obj, *mat;
    
    /* Check for missing port modifiers */
    if (!ambset [0])
-      error(USER, "no photon ports found");
+      error(USER, "no photon ports");
    
    for (i = 0; i < nobjects; i++) {
       obj = objptr(i);
+      mat = findmaterial(obj);
       
-      if (inset(ambset, obj -> omod)) {
+      /* Check if object is a surface and NOT a light source (duh) and
+       * resolve its material via any aliases, then check for inclusion in
+       * port modifier list */
+      if (issurface(obj -> otype) && mat && !islight(mat -> otype) && 
+          inset(ambset, objndx(mat))) {
          /* Add photon port */
          photonPorts = (SRCREC*)realloc(photonPorts, 
                                         (numPhotonPorts + 1) * 
@@ -550,6 +557,9 @@ void getPhotonPorts ()
          numPhotonPorts++;
       }
    }
+   
+   if (!numPhotonPorts)
+      error(USER, "no valid photon ports found");
 }